The Langkilde Lab in Action

Tag Archives: prescribed fire

My name is Richard Novak and I am finishing up my freshman year. I am in the Schreyer Honors College and I am studying Wildlife and Fisheries Science, with the Fisheries option. This is my second semester working in the Langkilde Lab. In fall 2017, I began working under Dr. Chris Howey as a research assistant helping with rattlesnake gestation site video monitoring. Currently, Dr. Howey and I are working on a study with macroinvertebrate communities in vernal pools and how they are impacted by prescribed fire. I was fortunate to receive an Erickson Discovery Grant which will allow me to continue working on this project into the summer. So far, I have developed my research questions and data collection methods, and I have been gathering data throughout spring semester. This research experience has been valuable to me for several reasons. First, I have been able to get a first-hand look at the entire experimental design and execution process, something I can only read about in classes. Additionally, interacting with graduate students and other faculty has been very influential when thinking about my future ambitions and career path potentials.

Vernal Pool within a previously burnt landscape

The purpose of this study is to compare macroinvertebrates communities in vernal pools with varying fire histories. Fire is being used as a forest management tool, which will create a more open landscape that some wildlife species may prefer. Additionally, these prescribed fires may promote the growth of new vegetation and increase food for wildlife within the forest. I am looking at water samples from 12 vernal pools; three that were burnt over once (in 2016), three were burnt and mowed over (in 2016; this is an additional disturbance to the landscape), three pools burnt over twice (in 2014 and 2016), and three vernal pools from a control group with no recent fire or disturbance history. Specifically, I would like to answer the question, “do prescribed fire practices alter the macroinvertebrate communities of vernal pools?” This question has been relatively unexplored in previous research. But preliminary data collected by Chris suggests that physiochemical (physical and chemical) characteristics of these pools are different, which could lead to differences in what macroinvertebrates are able to survive in these pools. I will analyze water samples collected from these vernal pools for macro-invertebrates, identify all macroinvertebrates found to family, and determine abundance of each family. The water samples that I have been going through now were collected in 2016, and additional samples will be analyzed from 2017 that are currently being collected. I look forward to getting out in the field this summer and assisting with measurements and collections.

This is what my lab bench typically looks like while I’m collecting data. My sorting tray with a sample spread out to the left, a hand-held magnifying glass, dissecting microscope, and the computer with my spreadsheet in the background. Note, there are also plenty of macroinvertebrate books to help me identify everything I find.

When I first began this project, I had to learn how to identify the macroinvertebrates to family. One of the reasons I am interested in macroinvertebrates is because of my interest in fly fishing, which requires basic knowledge of aquatic entomology, so I had some ID skills to bring to the table. I practiced using dichotomous keys to identify the specimens, a task I found time consuming but very learnable with practice. Now, I am very familiar with the families that I encounter most often. As of right now, I have identified the presence of over 20 families of macroinvertebrates among the vernal pools in the study. I find a lot of mosquito larvae (Culicidae), phantom midges (Chaoboridae), cased caddisflies (Limnephilidae and Odontoceridae), as well as several families of dragonfly and damselfly. To me, the coolest creatures that I find are fairy shrimp (Chirocephilidae) and water-boatmen (Corixidae) although I don’t come across either of those frequently.

Culicidae pupae. These will grow up to become the dreaded mosquito!

Chaoboridae larva. These are also known as phantom midges.

Limnephilidae larva. This is a type of caddisfly. Caddisflies are known to build these ‘houses’ out of sticks, leaves, and rocks within their environment. The actual larva is within this house made of sticks and you can see its head sticking out of the top. Different species of caddisflies will use different substrates to build their houses, so you can tell species apart based on the house materials.

Odontoceridae larvae. These are another species of caddisfly. You can see that they use a different substrate material for their houses.

Chirocephilidae larva. This is also known as a fairy shrimp and can be very common in many of Pennsylvania’s vernal pools.

Corixidae adult. These are also known as water-boatmen. They are typically seen swimming across the surface of a vernal pool, but can dive to the bottom when foraging or escaping a would-be predator.

So far, I am finding more mosquito larvae (Culicidae) in unburned pools. But among the burned pools, I am observing more mosquito larvae and caddisflies (Limnephilidae) in pools that were more disturbed (burned and mowed). This trend among the vernal pools is interesting, because that mow was an extra disturbance on top of the burn, yet these two families appear to be doing better in these pools. Please note though, these data are still being collected and these results may not accurately represent our final findings once we have analyzed all water samples.

Preliminary data for our macroinvertebrate communities within the four different treatments. In the future we will compare species diversity and richness among vernal pools. We will also see if there are any correlations between species presence/absence from vernal pools and the physiochemical characteristics of those pools.

Working on this project has been useful to me for many reasons. I have had a lot of fun sorting through samples and looking at the macroinvertebrates; it really never gets old to me which is good because I’ll be staring at trays a lot more this summer. It has been very satisfying to see my very own data begin to build on the spreadsheet as I work. Also, being around other lab members has given me a look into what school is like for graduate students. My freshman year is coming to a close, and I hope to take on new and exciting projects throughout the rest of my undergraduate career. When I came to college last fall, I did not expect to become involved in research right away, but I am very glad I took that step early and I have been fortunate in the opportunities presented to me. After graduating, I plan to pursue at least a master’s degree in a biology related field. I am interested in working for a natural resource management agency, although this experience has opened my eyes to the possibility of university research as a career. Whatever happens, my goal is to continue exploring more about biology and the organisms that fascinate me so much.

Even though I am continuing the same project from last year (how maternal stress affects the offspring in fence lizards), there are still some striking differences. One of the biggest is that there are fellow grad students and a post doc this summer!

From left to right: Cameron (PhD), myself (PhD), Kirsty (post-doc), and Dustin (PhD).

Also, last year we made the drive in one day, however this year we broke the drive up over 2 days. This gave us an excellent opportunity to experience different parts of the USA on our drive. For the night we stopped in Knoxville, TN and had dinner at an amazing place called Calhoun’s On The River. True to its namesake, it had a beautiful view of the Tennessee River!

After all the driving, we finally made it back to Solon Dixon and started catching lizards. As usual, the lizards’ personalities were very evident.

Male fence lizard unamused with our attempts to catch him

Apparently the female lizards found that corner of the tub to be very interesting.

As I went to put this female back in her tub, she refused to let go of my fingers!

On top of finding many fence lizards, we were also about to see many other reptiles and amphibians!

A barking tree frog tightly hugging my finger.

An American alligator, at a very reasonable size to handle.

A yellow bellied slider who found a little bit of water to sit in.

A glass lizard!

As I spend more time down here, I find it rubbing off on me more and more.

Very tempted to get a cowboy hat.

After catching the females, our first trip came to an end. However, we were quickly back down to release the females and run experiments with the hatchlings. With us this time we had an undergraduate researcher, Jen!

The Bayfront Park, overlooking Mobile Bay. Located right next to one of our field sites, Blakeley State Park.

As we wait for more hatchlings to emerge, we have been focusing on removing fire ants from some of the enclosures we built. As fire ants are highest in the mounds earlier in the day, this means some early mornings. On the up side, it also means we always get to see the sunrise.

Sunrise right near the enclosures.

Most things have gone well, with only one piece of equipment starting to show signs of wear, but this just gave me an excuse to do some handywork!

Used some steel epoxy to seal a leak in the pot we boil water in for fire ants.

Things have started to pick up in terms of hatchling, so soon you should be able to hear about how things are going with them. Until then, here is a pic from right here at Solon Dixon

Fire is landscape disturbance that can do great things for resident organisms. Certain plants and animals are adapted to cope with or even thrive in the earlier successional habitat created by this blistering disturbance. Serotinous pine cones that open following a fire, oak trees with thick bark protecting them from the heat of the fire, or grasses taking advantage of the nitrogen released in the post-fire soil. Small rodents like mice and chipmunks dive into burrows to protect themselves from the direct effects of a burn, only to re-emerge in a scorched world that will be filled with food, grasses and acorns, within a year. Other species like snakes and lizards may survive the fire and find a new forest with more sunlight reaching the forest floor and greater basking opportunities. Forestry managers have begun to reintroduce this natural disturbance back onto the landscape in the form of a controlled burn. And whereas some species may benefit from this disturbance, other species may not fare so well to the disturbance itself or the post-fire landscape. For many species, it is unclear how they will respond to prescribed fire.

The effects of prescribed fire on vernal pools and vernal pool amphibians remains largely understudied. Some amphibian species like Spotted Salamanders, Jefferson Salamanders, and Wood Frogs rely on vernal pools as an essential habitat where their eggs can be deposited and larvae can develop in the presence of a plethora of food and absence of fishy predators. These pools disappear each summer only to refill with winter rain and snow melt, just in time for spring migrating salamanders and frogs which lay their eggs among their submerged branches and vegetation. The eggs and larvae of amphibians can be highly sensitive to changes in water chemistry and temperature. As fire changes the landscape around a vernal pool, it may also influence characteristics of a vernal pool. Reductions in forest canopy may allow more light to reach the vernal pool and increase amphibian larvae growth rates. Run-off from the burnt forest floor may also increase alkalinity within the vernal pool. Following a series of prescribed burns in Florida, Clay Noss and Betsie Rothermel found a slight increase in vernal pool water pH; however, this change did not affect their focal species, the Oak Toad. So, would a similar change be expected from prescribed fires in the forests of Pennsylvania? Would amphibians native to our vernal pools respond in similar ways to the Oak Toad?

Jefferson Salamander eggs attached to a submerged branch.

Wood Frogs mating within a vernal pool. Large swollen eggs are present in the background as well as a freshly laid egg mass to the right.

These are just a few of the questions that I am looking to answer with a couple research projects I began this spring. Luckily, I have the assistance of a fantastic undergraduate, Michaleia Mead, who will stay on after she graduates this spring and turn some of these projects into her Masters thesis. For our first project, we began sampling the water chemistry (pH, dissolved oxygen, conductivity), temperature, and physical characteristics of a series of vernal pools with differing burn histories. We are also measuring the canopy cover over the vernal pools and the amount of UV-B radiation that may reach the water surface. UV-B is known to cause detrimental effects on amphibians in high enough doses. We want to see if vernal pools in an oak dominated forest respond to prescribed fires in similar ways to the vernal pools of Florida. We will sample invertebrate and amphibian abundance and diversity within these vernal pools. Do we see a change in community composition of a vernal pool as characteristics are altered by prescribed fire?

Vernal pool located in a post-burn landscape. This tract of land was burned in 2014. Note the charred trees in the background and reduction in understory vegetation.

To accompany the field projects, we began to raise Wood Frog tadpoles in the lab under different pH and UV-B conditions. We will determine if these changes affect tadpole development and survival. Additionally, we will compare corticosterone levels among tadpoles from different treatments to determine if certain treatments lead to more stressed tadpoles. Even if tadpoles survive and develop under certain conditions, developing under stressful conditions can result in increased energy expenditures and decreased fitness. This could have implications beyond the vernal pool if recently metamorphed Wood Frogs have lower energy reserves.

50 tadpoles are placed in each tank with varying amounts of pH and UV-B.

2015 ended in style for the Langkilde Lab, and we are proud to report that thus far 2016 has been just as exciting! In the last few months, we have celebrated a number of lab accomplishments and enjoyed some attention from the media. Here’s a taste of what we have been celebrating:

Press:

Penn State News featured the lab’s work on adaptation to invasive species and anthropogenic noise in this great article by Matt Swayne, complete with disco references. It’s definitely worth the read!

Penn State Science recently covered the lab’s research on the effects of stress, our collaborations, and Tracy’s mentoring style. The story quotes many lab members and also includes a “person-to-person” feature on graduate student Gail McCormick.

Other achievements:

PI Tracy Langkilde recently accepted the position as the Head of the Department of Biology.

Gail McCormick successfully defended her PhD dissertation and won the Alumni Association Dissertation Award. This award is among the most prestigious available to Penn State graduate students and recognizes outstanding achievement in scholarship and professional accomplishment.

Chris Thawley won the Intercollege Graduate Student Outreach Award, a university-level award that recognizes outstanding achievements related to bringing scholarship to the community. Chris will be defending in February and will be starting a post-doc with the Kolbe Lab in May, where he will be investigating the effects of urban light on anoles.

Kirsty MacLeod will be joining the Langkilde and Sheriff Labs as a post doc this spring. We are excited to have her!

Michaleia Mead will be staying on as a Masters student with Chris Howey. They will be investigating the effects of prescribed burns on amphibians and vernal pools.

Hooray!

Stay tuned throughout 2016 for more exciting research and updates from the Langkilde Lab!

Earlier today, I posted a blog which briefly discussed the projects that I will be conducting over the next two years. Two projects are looking at the effects of prescribed fire on herpetofauna. Yes, there may be direct effects as reptiles and amphibians may be caught up in the fire and may become injured or killed. But, many reptiles and amphibians will survive the fire and have to deal with the changes in habitat. But seriously, to what extent can a prescribed fire change the landscape? What exactly does a prescribed fire/controlled burn look like in action? My fantastic team of technicians will be assisting me this summer as we collect pre-burn data. Most of them will never see an actual prescribed fire. These are just some of the questions that may go through my technicians’ minds as they work for me this summer; some questions that may be going through your mind as well! So today we took a field trip away from our field sites to see a prescribed burn in action. After an 0800 briefing we set out to observe the burn in action. Everything went as smoothly as we could have hoped for, and the burn snuck its way through the forest consuming leaf litter, high-bush blueberry, low birch and maple saplings, and coarse woody debris. Flame heights mainly stayed pretty low, and nothing got out of control. Next summer my study sites will be burned as well, and we will be able to investigate the effects on timber rattlesnakes and vernal pool amphibians. Can. Not. Wait.

Another field season is underway and things are getting crazy! This summer, I will be conducting three big projects, but luckily I will have the assistance of a small army of technicians. The first project will focus on the habitat use and thermal biology of the timber rattlesnake and how prescribed fire may affect the availability of these preferred habitat characteristics. This summer we will radio-track rattlesnakes to determine thermal and habitat preferences. Next year, the study sites will be burned, and I will determine if these post-burn landscapes provide more or less habitat fitting these preferences. So far we are off to a great start! We have captured 21 rattlesnakes and we are radio tracking 5 males and 4 females (we hope to get a few more females). Next week we will begin to characterize the available habitat surrounding the rattlesnakes as we will begin vegetation surveys, measuring operative temperatures, and small mammal trapping.

In addition to investigating the effects of fire on timber rattlesnakes, I am also looking at the effects of prescribed burning on vernal pool amphibians. From time-to-time, prescribed burns are conducted right next to a vernal pool. This disturbance may reduce canopy cover over the vernal pool, raise temperatures within the vernal pool, and change water chemistry. Long-term effects may also include changes in soil composition surrounding the vernal pool which may lead to more run-off into the vernal pool. To determine these effects more clearly, I am measuring the physio-chemical characteristics of 4 vernal pools (2 that will be burned over next spring and 2 that will remain untouched). I have deployed weather stations in each vernal pool that will track water temperatures, air temperatures, relative humidity, wind speeds, rain fall, and amount of solar radiation reaching the vernal pool. I am also measuring DO, pH, and conductivity each time I visit the vernal pool, in addition to surface area and depth of the vernal pools. During these visits, I am surveying for larval amphibians, egg masses, and invertebrates. So far we have seen many wood frogs, Jefferson’s salamanders, and spotted salamanders. However, we seemed to skip “spring” this year and things warmed up very quickly. Two vernal pools completely dried up! And the other two are getting very shallow! We were able to add on another vernal pool to replace one that dried up, but things aren’t looking good for this year’s tadpoles and larval salamanders… Next year, we will burn over the vernal pools and investigate changes in water chemistry and physical characteristics of each pool.

A spotted salamander (Ambystoma maculatum) eggmass in one of the vernal ponds.

These salamander eggs are definitely ready for their close-up.

Working with one of the weather stations in a vernal pool (prior to the dramatic dry-down!)

Lastly, Mark Herr and I will begin a project looking at ecological trade-offs between thermal resource acquisition and predation at gestation sites of various sizes. We will be deploying operative temperature models and foam predation models at 6 gestation sites (3 small and 3 large sites). We will also radio track a couple gravid females at each site to determine body temperatures, survival, and lay dates. For more on this project, see Herr’s post! And for more on all of these projects, stay tuned to future posts!

Imagine you’ve passed your deadline for filing a report at work. The report isn’t finished and now you need to decide where you’re going to finish it. This is critical, because your boss hasn’t confronted you about it yet, and you just might get off scot-free if you manage to get it in soon enough. Here is the dilemma: If you work from home, you won’t see your boss and so won’t get a thrashing. Without running into you, your boss might not even recall the fact that you were supposed to submit the report, and you’ll get off free and clear. Your job fully permits you to work from home, but unfortunately you don’t have access to all of the company resources you need to get it done as efficiently as possible. It might take twice as long to finish from home, and if your boss already knows it’s missing you are going to be in even more trouble if it’s extra late. If you go into the office you’ll be able to finish the report in half the time and might get it submitted before anyone realizes it’s missing, but you’ll also risk the thrashing from your boss if he is aware. This is the type of situation that people encounter all the time: problems with multiple solutions, each with positives and negatives and no clearly superior alternative.

It just so happens that scenarios like these are common in nature as well, and how organisms respond to problems like these has important impacts on ecology and evolution. When we discuss the ways that organisms respond to problems like these, we refer to them as trade-offs: situations where an individual, population, or species gives something up in return for something else. It seems simple enough, but it turns out that this concept is tremendously important. For example, if a predator inhabits a landscape with diminishing prey resources, it may face a trade-off in how to respond. Some individuals may become more active in order to find more prey to sustain themselves, while others may take the opposite route and stop moving in order to conserve what energy they do obtain. In this way, a trade-off like this could result in one species diverging into two – an active forager and an ambush hunter.

This brings me to the research project that I’m going to be working on this upcoming spring and summer. I’ll be working with lab post-doc Chris Howey, who’s currently studying the way that proscribed fire impacts Timber Rattlesnakes here in PA. Chris is particularly interested in the impacts that these fires have on gravid (pregnant) female rattlesnakes.

So while I’ll be working with Chris helping him out on his larger project, we’ll also conduct a side project on the trade-offs that gravid female rattlesnakes make during the active season. Shortly after emerging from their winter dens, gravid female rattlesnakes will congregate in open rocky areas to incubate their developing embryos. Typically they stay at these spots, termed gestation sites, for nearly the whole active season – until they give birth to live young sometime in late summer. They are spending their time thermoregulating in order to develop their embryos as efficiently as possible, so it’s obviously important for them to choose sites with good thermal qualities.

This is where they might encounter a trade-off, though. The largest, most open rocky areas will have the most sun exposure, and so one would think they would be the best places for the snakes to choose as gestation sites. However, we think that these sites might leave the rattlesnakes even more exposed to predators than they would be otherwise – this is especially important because the snakes are already more vulnerable while out basking than they would be if they were foraging in the forest where their camouflage is most effective.

This past summer we found that some pregnant females chose smaller, more closed canopy spots with less sun exposure as their summer gestation sites. Why would these rattlesnakes be choosing sites like this when big open sunny spots are available? We think that this might be a classic ecological trade-off: with snakes weighing the thermal quality of the spots with the risk of being attacked by predators.

This rattlesnake is doing a terrible job of trying to avoid predators.

This might be what’s going on, or it might not. Perhaps the snakes are just choosing the spots that are closest to where they denned up. Maybe the closed spots and the open spots don’t even have different predation risks attached to them! We’re interested in exploring this issue to see if this is really what’s going on, and understanding this dynamic might help conservation authorities understand the ways that a species under threat (like timber rattlesnakes here in the Northeast) use the different parts of their habitat.

In order to test to see whether a trade-off really is occurring, we’ll be assessing the different gestation spots chosen by rattlesnakes for their thermal qualities and predation risk. To test the thermal quality we’ll analyze the sun exposure of these sites and we’ll place thermal models designed to mimic rattlesnakes and analyze them against the preferred body temperatures of live rattlesnakes that we measure in the lab.

How will we measure predation risk? This is the part that I’m working on right now in preparation for this summer. We are making realistic foam rattlesnake models that we are going to set out at the different sites. The foam that we are casting the snakes in should hold the imprint of attack from the predators and should give us some idea of what type of predator went after our snakes! This is a technique that’s been used before (on rattlesnakes no less!) by Vincent Farallo to quantify the risk of predation, and we are excited to use it to test our hypothesis!

Making these foam models is taking up most of my time on this project right now, and we are going to need a couple hundred by the time spring starts, so I’m busy! I’ll post more updates on the project here on the Lizard Log in the future as we get rolling – but I’ll leave you off with some photos of the model making process that’s taking up my time now while there’s still snow on the ground!

The first step in making our models is to get an actual snake to cast them from! We took this preserved timber rattlesnake specimen from the teaching collection here at Penn State to make our mold for the future specimens.

Then we posed her in a typical basking rattlesnake position – getting the snake like that isn’t as easy as it seems! When specimens are fixed in formalin during the preservation process it tends to make them rigid and tough to work with, but we managed!

After this we poured a rubber mold compound in the tray and let it set, then we removed the preserved snake and voila – snake mold!

Here you can see we’ve just poured the mixture into the mold – it will then quickly expand to fill the whole mold and once it hardens…

We’ve got our rattlesnake model! The only step after this is painting it to make it look like an actual basking rattlesnake!

Here’s a painted model; painting them is by far the most tedious part of the process, as the rattlesnakes have pretty intricate patterns. By the start of the project I’m going to need a couple hundred of these things painted and ready to go. It’s gonna be a busy semester!